TOLEDO, Ohio — If there’s any state capable of finally bringing order to the Republican presidential primary, this is it.

As the 2012 primary battle spreads across the Super Tuesday landscape, the sound of the guns is loudest in Ohio, where Mitt Romney is spending big sums to reclaim his front-runner status permanently — and his conservative opponents are banking on one more dramatic, campaign-shifting upset.

Ohio allocates its 66 presidential delegates proportionally so it’s unlikely that any candidate will achieve a decisive advantage in that realm. But of all the primaries left on the calendar, none carries quite the same symbolic weight as Ohio, a premier general election battleground at the center of the industrial Midwest.

Public and private polling suggests the race here is a competitive fight between Romney and Rick Santorum. Quinnipiac University gave Santorum a 7-point lead over Romney earlier this week. Private polling conducted for Republicans outside the presidential race, and shared with POLITICO, showed Santorum up by 5 percentage points.

But conservatives and even Democrats — who have sought opportunities in the primary to weaken Romney for the general election — are still in a position to make Romney sweat in Ohio. Local politicos caution that the race could take yet another unpredictable turn in a contest that’s featured many.

“There’s a great deal of volatility,” said Ohio Secretary of State Jon Husted, a Republican who has not endorsed in the primary. “I think there’s a lot of calculating going on. There are people who want to beat Barack Obama and there are people who want to send a message, and they’re trying to decide if they need to choose or whether they can do both.”

Though the campaigns and super PACs have already spent heavily on TV and radio ads, Husted said Ohio’s swing-state status means voters may not be overly swayed. “We’re so used to what I would call political noise. … They kind of tune out all the noise until they have to make a decision.”

Bob Bennett, the former longtime Ohio GOP chairman, diagnosed the race as “neck-and-neck” thanks to Romney’s Michigan win, adding the odds are strong for a close finish.

“I do not anticipate that either Romney or Santorum” will win a majority, Bennett predicted. “I think ultimately Romney will win.”

He pointed out that Santorum would nevertheless collect delegates from conservative areas in the southwestern part of the state.

Campaigns and independent groups have already spent approximately $5 million on TV and radio ads in Ohio, according to media-tracking sources. Restore Our Future, the super PAC supporting Romney, has on its own reserved $1.1 million in airtime between Feb. 27 and Super Tuesday. Romney has also moved several key aides from his successful Florida campaign to Ohio in recent weeks.

Multiple new groups have joined the fray in just the past 24 hours. The Susan B. Anthony List, an anti-abortion rights group supporting Santorum, has announced plans for $200,000 in radio ads. Earlier this week, the public-sector labor giant AFSCME began running negative ads against Romney.

Also from the Democratic side, the pro-Obama super PAC Priorities USA Action is starting to air television commercials in the Columbus media market swatting Romney for his views on workers and federal intervention in the auto industry. Romney opposed the auto bailout and Democrats believe while that stance may have helped in the primary, it will be devastating in the general election. Ohio has a closed primary but voters can change their party registration on primary day.

Priorities USA strategist Bill Burton said that as the primary moves to key general election states like Ohio, Democrats see an opportunity to wound Romney for the long term. He likened it to the effort in Michigan, by Democrats and labor unions, to force Romney on the defensive on the auto bailout.

“That fight and the attention on Mitt Romney and the auto bailout basically made [Michigan] non-competitive for the general election,” Burton argued. “We’re looking at Ohio and deciding what makes the most sense in terms of making sure that he’s held accountable.”

A Romney victory in Ohio would reinforce the core of his argument to Republican primary voters: he’s a candidate who can win in the states that matter most and his economic proposals are right for the country’s distressed areas.

Winning Ohio would also ensure that Super Tuesday is viewed as a good night for Romney, regardless of what happens elsewhere on a primary map laden with less Romney-friendly states. And it would give Romney another major victory as the primary season advances through tough Southern states such as Alabama and Mississippi, which vote on March 13.

To some Romney supporters, taking the Buckeye State seems like the best opportunity in some time — maybe since South Carolina — for Romney to signal that it’s time for the GOP to rally around him.

“I certainly would hope that a win in Ohio would persuade the doubters that it’s time to get behind Gov. Romney and focus our attention on Barack Obama,” said Ohio Senate President Tom Niehaus, who recently endorsed Romney. “But this is a long primary process and I’m sure there are people in other states who want to have the opportunity to weigh in with their opinions.”

Said Niehaus: “Voters are still very much watching what’s happening in the media, listening to what candidates have to say. Based on conversations I’ve had with people, a lot of people haven’t made their final decision.”

Perhaps most important, the outcome in Ohio will either confirm Romney as the candidate who wins in Midwestern battlegrounds or reopen the question of whether he’s capable of wooing the blue-collar, working-class voters who will help decide the general election.

Among Romney’s opponents, only Santorum currently appears to have a chance at knocking him off course in Tuesday’s Ohio vote. Newt Gingrich is far behind in Ohio primary polling and while the super PAC backing Gingrich has spent more than $400,000 in Ohio, there is little time left for him to make up ground. Ron Paul has yet to win a single primary or caucus.

Also, over 100,000 early ballots have already been cast, according to Husted — most of those ballots in a phase of the race dominated by the Romney-Santorum duel and during which pro-Romney forces had a virtual monopoly on the Ohio airwaves.

If Santorum manages to maintain his hold on Ohio conservatives despite the outcome of this week’s primaries, then the political world could easily find itself back where it was a week ago: that is, in a nearly even two-man race between an establishment favorite rejected by the grassroots and a conservative challenger with serious flaws.

Ohio Attorney General Mike DeWine, who defected from the Romney camp to endorse Santorum, expressed confidence that’s exactly what would happen, predicting that Romney would be hobbled in Ohio by the same political deficiencies that he’s struggled with all along.

“There’s just no enthusiasm for Romney at all,” DeWine said. “He’s still making these mistakes, talking about his wife and two Cadillacs, knowing the NASCAR owners and not being a fan. … I don’t know how you make those mistakes. What it tells you is he’s not getting any better and he isn’t going to get any better.”

DeWine said he didn’t expect Santorum to suffer badly due to Michigan’s ouctome but acknowledged that Tuesday’s elections “make [Ohio] even more important for both sides. Ohio is very important and I think everybody knows what’s at stake here.”

“There’s more energy on the ground for Santorum and Romney’s got more money,” DeWine said. “That’s where the race is.”

In Ohio, many of the decisive voters will be blue-collar or middle-class whites in the suburbs and former manufacturing towns who have bounced between Romney and his challengers all cycle.

Much as he did in Michigan, Romney will have to decide how far he must run to the right in order to win. He has already tacked in a conservative direction on certain hot-button Ohio issues, backing a national right-to-work law banning mandatory union membership and endorsing the restrictive union regulations passed last year by Republican Gov. John Kasich that were subsequently struck down in a referendum.

That’s not a turnoff in a Republican primary, as Romney supporter Kathie Zaper made clear at a Romney rally in Toledo on Wednesday.

“We have lost so much and it’s all because of the unions,” she said. “One thing [Romney] needs to do is take it to the people, tell the people that he’s going to take it to Obama — no-holds-barred. Stop saying he’s a nice guy. He’s evil. [Romney] needs to stop saying he’s a nice guy.”

That’s not necessarily the right way to deal with all Democrats, Zaper added, explaining that she disliked Santorum’s comment that he wanted to “throw up” after reading John F. Kennedy’s 1960 speech on religion and politics.

“You don’t slam Kennedy like that,” she said.

At a Santorum stop in Perrysburg the day before, another Ohio voter invoked Kennedy in an entirely different light, underscoring the extent to which older, white and, in many cases, Catholic voters are key in the primary.

“When he came on the scene, I liked him, but I didn’t think he could make it,” Bill Gray, a Northwood resident, said of Santorum. “This is the man who can beat Obama.”

Asked why he thought Santorum was the strongest choice for the fall, Gray answered: “I just know it, like I knew it about Kennedy back in ’60.”